#define _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>
float fun(float* a, int n)
{
	float num = 0;
	for (int i = 0; i < n; i++) {
		num += *a;
		a++;
	}
	return num / n;
}
void main()
{
	int i;
	float score[5], aver;
	for (i = 0; i < 5; i++)
		scanf("%f", &score[i]);
	aver = fun(score, 5);
	printf("%5.2f\n", aver);
}